Human Population:
Growth, Demography and Carrying Capacity
Chapter 11
Miller 11th Edition
AP Environmental Science
LCHS
Dr. E
Human Population Growth Historically
A.
Early Hunter Gatherers
1.
2.
B.
Nomadic, With a Strong Sense of the Earth
Practiced Intentional Birth Control
Rise of Agriculture
1.
Necessary for Survival
Animals became extinct via predation and
altered habitat
b. Humans began to cultivate own food
a.
C. Agriculture Gives Rise to Cities
1.
Food Produced in Country, Consumed
in City
a.
b.
Food wastes are no longer returned to
soil
Soil becomes less productive
Waste of Populations Concentrated in
Cities
3. Population Control in Medieval
Societies
2.
a.
b.
Infanticide
Plagues
D. Industrialization
1.
View of Children During Early Phases of
Industrial Growth
Valued as cheap source of income and cheap
labor
b. Exponential growth of populations
a.
2.
By 1900s, Birth Rate in Industrialized World
Dropped
Rise in standards of living
b. Safe and inexpensive means of birth control
introduced
c. Increase in the cost of child rearing
a.
10000
developed countries
less developed countries
8000
M
I
L 6000
L
I
O
N 4000
S
2000
0
1750
1950
1995
2025
2100
Population
Projections
Over 95% of this
increase
will take place in
“Developing
Countries”
Current World Population
• Population Clock
Vital Events (per time unit)
Global population was 6,379,870,732
On November 2, 2004 at 11:05 am
• The global population grows by:
– Nearly 2.3 persons per seconds
– Nearly 8,343 persons per hour
– Over 200,234 persons per day
– Over 73 million persons per year
How Much is a Billion?
• 1,000 seconds = 16.7 minutes
• 1 million-s = 16,677 min = 11.6 days
• 1 billion-s
= 11,574 days = 31.7 years
• 1,000 pennies = ~ 88 ounces = 5.5 pounds
• 1 million pennies = 5,500 pounds (~1-Suburban)
• 1 billion pennies = 2,750 tons (~2 Space Shuttles)
Human Population Outline
• Factors Affecting Human Population Size
• Population Age Structure
• Influencing Population Size
• Carrying Capacity
Human Population Dynamics
• There are just three sources of change
in population size —
1. fertility
2. mortality
A. "natural decrease" refers to population
decline resulting from more deaths than
births
3. migration
– Net migration is the number of immigrants
minus emigrants
Rates of Global Pop. Change
use: International Data Base http://www.census.gov/ipc/www/idbnew.html,
then Online Demographic Aggregation
• CBR (crude birth rate) = # births / 1000 population
1990: 24
now: 20.6
• CDR (crude death rate) = # deaths / 1000 population
1990: 9
now: 8.8
• Growth Rate = (b + i) – (d + e)
1990: 1.5%
– growth rates have come down
now: 1.19%
Human Population Dynamics
• Total fertility rate (TFR)
–
–
–
–
The average number of children born to a woman
Average in developed countries = 1.5
Average in developing countries = 3.8
Worldwide 1990: 3.1 now: 2.76
• Replacement fertility rate (RFR)
– The number of children a couple must have to replace
themselves
– A TFR of 2.1 for developed countries with low infant
and child mortality rates
– Africa RFR = 2.5
What Is Family Planning?
A. Definition
1. Measures enabling parents to control number of
children (if they so desire)
B. Goals of Family Planning
1. Not to limit births
2. For couples to have healthy children
3. For couples to be able to care for their children
4. For couples to have the number of children that
they want
B.
China’s Program
1. Nation With Best Known Population Control Program
2. Reasons Chinese Government Initiated Population Control
Measures
a. Freshwater and food at a premium for nation’s population
b. Country experiencing population momentum
3. Government Perks / Coercive Measures for Citizen
Compliance
a. Free education and health care
b. Increased personal and family incomes
c. Increased legal marrying age for women
d. Contraceptives, abortions, and sterilizations free of
charge
e. Preferential housing and retirement income
What Methods are Used to Control Births?
A. Preconception Birth Control Methods
1. Barrier Methods
a.
b.
c.
d.
Condom
Vaginal sponge
Diaphragm
Spermicides
2. Hormonal Contraceptives
a.
b.
Pill
Injections and implants
3. Sterilization
B. Postconception Birth Control Measures
1. Intrauterine Device
2. RU-486 Pill
3. Abortion
Contraceptive Use Worldwide
People in industrialized countries enjoy easy access to
contraceptives while those in LDCs do not.
2. In the U.S., teens and poor women are least likely to use
contraceptives.
3. Severe problems are associated with teen pregnancy.
1.
Teens don’t receive the care they need.
b. More adolescent girls die from pregnancy-related causes than
any other cause.
c. Maternal mortality is twice as high for women younger than
20, and 4 times as high for women younger than 17.
d. Each year about 15 million young women ages 15-19 have
babies.
e. Survival rate for babies born to teens is low.
f. Young age of mother can cause problems with the child.
g. Teen pregnancy causes greater public expenditures.
a.
Human
Population
Dynamics
• infant mortality rate
• IMR
• infant deaths per 1000 live
births (infant < 1 yr)
– 1990: 62
now: 52.4
(normal in 1900: 200)
http://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality2.htm
www.tte-online.com/.../table-of-contents/ chem-enc-1.html
Maternal Deaths per 100,000 Live Births
Source: WHO, UNICEF, UNFPA Maternal Mortality in 1995: Estimates Developed
by WHO, UNICEF AND UNFPA, 2001.
Migration
Net migration is
the number of
immigrants
minus emigrants
•
•
•
Overall, the world
population is growing
at a rate of about 1.7
per cent; if this rate
continues, the
population will double
in 42 years.
Unabated, such a rate
would lead to a point
about 2000 years
hence when the mass
of humanity would
weigh more, and be
larger, than the Earth.
But, the growth rate
is decreasing
Human Population Outline
• Factors Affecting Human Population
Size
• Population Age Structure
• Influencing Population Size
• Carrying Capacity
Population Pyramids
• Graphic device: bar graph
• shows the age and gender composition of a
region
• horizontal axis: gender
– male: left-hand
female: right-hand
– absolute number of people or %
• vertical axis: age
– 5-year or 10-year age groups
Population Pyramid with
young cohorts
85 OR
80-84
75-79
70-74
65-69
60-64
55-59
50-54
45-49
female
male
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
-500
-400
-300
-200
-100
0
100
200
300
400
500
Population Pyramids
• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Austria or Italy
Population Pyramids
• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Austria or Italy
Population Pyramids
• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Austria or Italy
Population Pyramids
• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Italy
Demographic Transition
•
•
Movement of a nation from high population
growth to low population as it develops
economically
Transition as a result of four stages
–
–
–
–
Stage 1—Birth and death rates are both high
Stage 2—Death rates fall; birth rates remain high;
growth rate rises
Stage 3—Birth rates fall as standard of living
rises; growth rate falls
Stage 4—Growth rate continues to fall to zero or
to a negative rate
The Demographic Transition
Five Stages of the Demographic
Transition
• Used to be 4, now 5 stages
• birth rates, death rates and growth rates
systematically change through time as
societies change:
– modernize, urbanize
– gain access to technology
Stage 1
• high birth rates, high
(at time erratic) death
rates, low growth
rates
• stage for much of
human history,
traditional societies
• practically no country
today
Stage 2
• high birth rates,
declining death rates,
rising growth rates
• improvements in
sanitation (water)
and medicine
• in Europe during Industrial Revolution
• in developing countries since the 50s/60s
• much of Africa today, some countries of Asia
(Afghanistan, Nepal, etc.)
Stage 3
• continued decline of death
rates, declining birth rates,
growth rates decline from
high to lower levels
• change in behavior: adaptation to lower death rate,
in particular infant mortality rate
• economic change: urbanization (incentive to have
fewer children)
• Mexico today
Stage 4 & 5
• Stage 4: low birth rates,
low death rates, low
growth rates
– United States today
• Stage 5: low birth rates, rising death rates, declining
growth rates (if birth rates drop below death rates:
negative growth rates)
– several countries of Europe today (Austria)
Population Pyramids and
Demographic Stages
• characteristics shapes of ‘pyramids’
–
–
–
–
wide base (true pyramid)
wide middle (bulge), somewhat wider base
urn- or bottle-shaped
reversed pyramid
• different shapes--different dynamics
Population Pyramid and Demographic Transition
• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base
Population Pyramid and Demographic Transition
• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base
Population Pyramid and Demographic Transition
• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base
Population Pyramid and Demographic Transition
• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base
Demographic Trap
•
•
Population Path of Most Less-Developed
Countries (LDCs)
“Trapped” in Stage 2 of Demographic
Transition
–
–
–
–
Before 1970, LDCs seemed poised to make
transition thanks to economic growth
Since 1970, economic growth has not kept
pace with population
High birth and low death rates result in
explosive population growth
Downward spiral in standard of living
Demographic Fatigue
– Condition characterized by a lack of
financial resources and an inability
to deal effectively with threats such
as natural catastrophes and disease
– Possibility that countries suffering
from demographic fatigues could
slip back into Stage 1 of
demographic transition
Human Population Outline
• Factors Affecting Human Population Size
• Population Age Structure
• Influencing Population Size
• Carrying Capacity
Age Structure & Population Projections
• Baby boomers - half of U.S. population; use most
of goods and services; make political and
economic decision
• baby-bust generation - born since 1965; may have
to pay more income, health care and social
security to support retired baby boomers; but face
less job competition
• Better health may --> later retirement of baby
boomers --> keep high-salary jobs
Tracking the baby-boom generation in the United States
Effects of Population Decline
• As percentage of 60+ aged people increases,
population begins decline
• 60+population increase --> severe economic and
social problems because 60+ consume
– more medical care
– Social Security
– costly public services
• Labor shortages require automation &
immigration
The Graying of Japan
• Family-planning access, cramped housing,
expensive land, late marriage, education
cost --> voluntary decrease in birth rate
• Low immigration rate
• Health insurance and pension - 45% of
national income; could -->low economy
• Illegal immigration bolsters work force
Influencing Population Size
• Most countries restrict immigration
– Canada, Australia, U.S. - most immigration
• Involuntary immigration results from
– armed conflict
– environmental degradation
– natural disaster --> environmental refugees
• ~1% of developing nations pop. Emigrates
• Migration from rural to urban areas
Family Planning: reduce births and
abortions
• 59% contraceptive use in developed
countries -46% overall, up from 10% in 60s
• FP reduces children's social services needs
• FP reduces risk of childbearing deaths
• FP effectiveness depends on program design
and funding:
– good in some counties with good program
– poor in other counties
Family Planning: reduce births and
abortions -2
• Services not always accessible; add female
teenagers and sexually active unmarried
• Add birth control for men (sperm-killing
device used in China)
• If developed countries provided $17 billion/
year, and each person pays $4.80/year,
average family size would be 2.1 and world
population would be 2.9 billion
Rewards and Penalties to reduce births
• What might work:
– encourage, rather than coerce, people to have
fewer children
– reinforce existing customs and trends toward
smaller families
– don’t penalize for already existing larger family
– increase poor family’s economic status
Empowering women to reduce births
• Women tend to have fewer, and healthier
children when:
– they have access to education and paying jobs
outside home
– their society doesn’t suppress women’s rights
• But women do most of the work
– not shown in GDP because of lower pay
– Women excluded from economic and political
decision making
Case Studies - India
• Family planning efforts began in 1952;
fertility rate declined from 5.3 to 3.4 but
population grow is still exponential -1.9%
• Disappointing results due to:
–
–
–
–
–
poor planning
bureaucratic inefficiency
low status of women
extreme poverty
lack of administrative & financial support
Case Studies - China
• Family planning efforts began in 1970; TFR
fell from 5.7 to 1.8; infant mortality and
illiteracy rates 1/3 to 1/2 of India’s rates
• Population control program is extensive,
intrusive and strict:
– postpone childbearing
– only one child/family -->benefits
– effect b/c China is dictatorship; limited
resources would have mean disaster
Cutting Global Population Growth
• U. N.Conference on Population and
Development, Cairo, 1994
– 8 goals to be met by 2015 (p. 276)
– are these goals wishful thinking?
• Replacement level fertility can be met in
15-30 years as shown by Japan, Thailand…
• Invest in family planning, reduce poverty,
and elevate status of women
Short of thermonuclear war itself,
rampant population growth is the
gravest issue the world faces over the
decades immediately ahead. If we do
not act, the problem will be solved by
famine, riots, insurrection and war.
Robert S. McNamara
Sustainable Cities: Urban Land
Use and Management
Chapter 26
Miller 11th Edition
Definitions
• Urban (metropolitan) area = town plus its
suburbs
– City = large number of people with a variety of
professions who depend on resources from the
outside of city boundary
• Rural area = an area with a population less than
2,500 people
– Village = group of rural households liked by custom,
culture,family ties. Historical utilization of natural
resources
Urbanization & Urban growth
• Degree of urbanization is percentage of population
living in area of greater than 2,500 people
• Urban growth due to:
– natural increase - births
– immigration - poor are pulled to urban areas or are
pushed from rural areas
• Trends of urban growth:
– Increase of 2% to 45% of people in urban areas since
1950
– By 2050 about 66% of the world’s people will be living
in urban areas.
Urbanization & Urban growth
• The number of large cities is mushrooming
– megacities and megalopolis
– Today, more than 400 cities have over 1 mil. or more
people. 19 megacities with over 10 mil. People
i.e.Tokyo (28 mil), Mexico City (18 mil), New York (17
mil).
• Most of growth in developing countries will be
urban growth with all of its problems
– 38% of the people in live in cities. But by 2025 it will
be 54%. Many of these cities are already short on water,
have waste & pollution problems.
Urbanization & Urban Growth
• Urban growth is slower in developed countries
– 75% of the people live in cities. But by 2025 it will be
82%.
• Poverty is becoming increasingly urbanized
– slums, squatter settlements and shantytowns
– at least 1 billion people live in crowed slums of inner cities.
No access to water, sewer, electricity, education etc. 100 mil
people are homeless & sleep on the streets
• Case study - Mexico City
Mexico City
• The world’s second largest city with 18 million
people or one in five Mexicans
– severe air pollution (over 4 million cars) within a valley
that causes an estimated 100,000 premature deaths/year
– high unemployment rate, close to 50%
– high crime rate
– over one-third (6 million) of its residents live in slums
(barrios) without running water, sewer (but running
sewage), or electricity
– high infection rates i.e. salmonella, hepatitis
United States Urbanization
•
•
•
•
Migration to large central cities
Migration from cities to suburbs
Migration from north & east to south & west
Urban sprawl, growth of low-density development
on the edge of cities. Encouraged by:
- availability of cheap land, (forests, agriculture fields etc.).
- government loans guarantees for new single-family homes
- government & state funding of highways
- low-cost gasoline encourage car use
- low interest mortgage
Major Spatial Patterns
• Concentric Circle City such as New York
• Sector City is the large urban area extending
from San Frdancisco to San Jose, CA
• Multiple Nuclei City is Los Angeles
• Megalopolis is when separate cities join
such as the Bowash
Concentric Circle Model
1.
2.
3.
4.
5.
Central business district (CBD)
Deteriorating transition zone
Worker’s homes
Middle-class suburbs
Commuter's zone
Sector Model
1.
2.
3.
4.
5.
6.
7.
High-rent residential
Intermediate-rent residential
Low-rent residential
Education and recreation
Transportation
Industrial
Core (CBD)
Multiple-Nuclei Model
1.
2.
3.
4.
5.
6.
7.
8.
9.
CBD
Wholesale, light manufacturing
Low-rent residential
Intermediate-rent residential
High-rent residential
Heavy manufacturing
Outlying business district
Residential Suburb
Industrial Suburb
Major Urban Problems in U.S.
• Deteriorating services
• Aging infrastructures
• Budget crunches from lost tax revenues as
businesses and affluent people leave
• Rising poverty with violence, drugs, decay
• Urban sprawl - growth of low-density
development on edges of cities and towns
– 9 consequences of “bad growth”
75% of the US population live
in urban areas occupying 3%
of the country’s land area
Urban Resources & Environmental Problems
• 45% of people living in 5% of land – cities –
consume 75% of the world’s resources
• Urban areas depend upon imports
• Benefits of urbanization:
– recycling more economically feasible
– decreased birth rates reduces environmental pressures
– per capita expenditures on environmental protection
high in urban areas
– population concentration impacts biodiversity less
Urban Resource and Environmental
Problems
• Destruction of plant life - what is $ value?
• Cities produce little of own food
• Urban heat island effect --> dust dome
– 5 ways to counteract this effect
• Water supply and flooding problems
– 5 ways to reduce demand on reservoirs and
waste treatment systems
• High pollution exposure
•The enormous amount of heat generated creates an urban heat island
•Additional heat changes climate of surrounding area
Urban Resource & Environmental Problems
• Excessive noise exposure  health effects
– Hearing loss, hypertension, muscle tension,
migraines, headaches, higher cholesterol levels,
gastric ulcers, irritability, insomnia,
psychological disorders, aggression
Urban Resource & Environmental Problems
• Beneficial effects:
– education
– social services
– medical care
• Harmful effects
– infectious disease spread
• high density population
• inadequate drinking and sewage system
– physical injuries
– pollution exposure
– Urban Sprawl
Impacts of Urban Sprawl
Land and Biodiversity
Water
Human Health
and Aesthetics
Increased runoff
Contaminated drinking
water & air
Increased surface water
& groundwater pollution
Noise pollution
Increased use of surface
water & groundwater
Loss of cropland
Loss of forests &
grasslands
Loss of wetlands
Loss & fragmentation of
wildlife habitats
Increased wildlife road kill
Increased soil erosion
Sky illumination at night
Decreased storage of
Surface water &
groundwater
Traffic congestion
Increased flooding
Decreased natural
Sewage treatment
Impacts of Urban Sprawl
Energy, Air, and Climate
Economic Effects
Increased energy use
and waste
Higher taxes
Increased air pollution
Decline of downtown
business districts
Increased greenhouse gas
Emissions
Enhanced global warming
Warmer microclimate
(heat island effect)
Increased
unemployment
in central city
Loss of tax base in
central city
Transportation and Urban Development
• Determines where people live, where they
go to work and buy stuff, how much land is
paved and exposure to air pollution
• Cities grow up if they can’t grow out; more
prone to use mass transit
• Urban sprawl due to cheap gas and land and
highways; dispersed car-centered cities use
10x more energy
Motor vehicle concentration
• Ground transportation: individual (cars, etc) and mass
(buses and rail)
• U.S. has 35% of cars and trucks used for 98% of all
urban transportation
• Motor scooters - effort to change to electric
Drive alone 80%
• Riding bicycles;
less pollution and
dangerous and more
efficient than
walking
Other 4%
– bicycles available
for public use
– bike and ride
systems
Public transit 5%
Car pool 11%
Pros and Cons of Mass transit
• 3% mass transit use in U.S. to 47% in Japan
• 20% gasoline tax revenues to mass transit
• Rapid rail, suburban trains and trolley - efficient
at high population density
• High speed rail lines – replace planes, buses and
private cars; but require large government
subsidies
• Bus systems more flexible than rail systems but
efficient when full